the problem is that 3cx extensions and services have been going offline every night since the day before yesterday. and every time I have to restart the raspberrypi where can i find the logs so i can send that here
It appears that you've installed the Raspberry Pi incorrectly (you've installed the full Pi OS), I suggest following the Raspberry Pi installation guide here (which is the same for 3B+): https://www.3cx.com/docs/installing-pbx-raspberry-pi/
Yes, I believe that installing a more resource intensive OS would have an influence. The PBX was tested on the Pi and the supported method of installation developed, thus its advised to follow it.
The backup and restore function in the Management Console outlines all criteria that can be backed up and restored. You can reset the password before backing up and reinstalling, by navigating to Security >> Security Settings then Admin Credentials and resetting the password.
If you do not remember the password, there is a management console "Forgot password" link that appears after entering the correct username but incorrect password twice (note, the third time will force a lock out).